Heavy Snow in Oregon, January 7 to 9, 2008

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
937 PM PST MON JAN 7 2008

UPDATED SHORT TERM AND AVIATION DISCUSSION

.UPDATE...A LARGE MOIST PACIFIC FRONTAL SYSTEM HAS BEGUN TO MOVE
INLAND THIS EVENING. PRECIPITATION HAS ALREADY BEGAN FALLING IN
CENTRAL OREGON AND ALONG THE CASCADES AND EASTERN SLOPES...AND IS
EXPECTED TO CONTINUE TO SPREAD NORTHWARD AND EASTWARD OVERNIGHT. BY
TOMORROW MORNING...SNOW IS EXPECTED NOT ONLY ALONG THE
CASCADES...BUT IN MOST OF THE HIGHER TERRAIN OF CENTRAL AND
NORTHEAST OREGON AND SOUTHEAST WASHINGTON...LASTING THROUGH
WEDNESDAY. THE LOWER COLUMBIA BASIN AND NORTH CENTRAL OREGON WILL
LIKELY EXPERIENCE RAIN DURING THE DAY ON TUESDAY...DUE TO THE
PRESENCE OF A STRONG WARM FRONT THAT IS FORECAST TO PUSH THROUGH THE
AREA. THE RAIN SHOULD THEN CHANGE OVER TO SNOW OR A RAIN/SNOW MIX ON
TUESDAY NIGHT AS THE COLD FRONT MOVES INLAND. MULTIPLE WARNINGS AND
ADVISORIES HAVE BEEN ISSUED IN RELATION TO THIS MAJOR WINTER STORM.
PLEASE REFER TO PRODUCT ID PDXWSWPDT FOR MORE DETAILS.  CALDER

.AVIATION...CLOUDS WILL CONTINUE TO INCREASE OVERNIGHT. MVFR/IFR
CONDITIONS WILL BE POSSIBLE IN RAIN AND SNOW AT KDLS...KRMD AND KYKM
THROUGHOUT THE NIGHT. MVFR/IFR CONDITIONS WILL THEN SPREAD EAST
ACROSS THE REMAINDER OF AREA BY 12Z...DUE TO LOWER CEILINGS AND
REDUCED VISIBILITIES WITH RAIN AND SNOW. THESE CONDITIONS ARE
EXPECTED TO LAST THROUGH THE DAY ON TUESDAY AND INTO TUESDAY NIGHT.
WINDS SHOULD GENERALLY REMAIN BELOW 15 KTS.  82

&&

.PREV DISCUSSION... /ISSUED 204 PM PST MON JAN 7 2008/

SHORT TERM...TONIGHT THROUGH WEDNESDAY...SIGNIFICANT WINTER SYSTEM
IS POISED TO IMPACT THE MID AND HIGH TERRAIN BEGINNING MAINLY AFTER
MIDNIGHT TONIGHT AND LASTING INTO WEDNESDAY. TROUGH THAT WILL CROSS
THE AREA HAS AM AMPLE SUPPLY OF MOISTURE STRETCHING TO THE WEST OFF
THE CALIFORNIA COAST AND NORTH OF HAWAII. SATELLITE PW ESTIMATES
INDICATE VALUES RANGING BETWEEN 1.5 AND 2.5 INCHES OF AVAILABLE
MOISTURE. PRECIPITATION IS EXPECTED ACROSS THE CREST AROUND
MIDNIGHT. LITTLE SHADOWING IS EXPECTED AS MID-LEVEL WARM (RELATIVELY
SPEAKING) PROCESS PRECIPITATION WILL INITIALLY DOMINATE WITH SNOW
LEVELS MAINLY BETWEEN 1000 AND 2000 FEET WITH LIGHT ACCUMULATIONS
BELOW 1000 FEET. THE MAIN SURGE OF WARM AIR AT 850MB WILL PASS
ACROSS CENTRAL OREGON AND THE LOWER BASIN TUESDAY MORNING AND EARLY
AFTERNOON AND WILL BRING SNOW LEVELS GENERALLY TO THE 3000-4000 FEET
RANGE. WASHINGTON CASCADES...HIGHER PASSES OF THE OREGON
CASCADES...AND THE NORTHEAST MOUNTAINS OF OREGON WILL CONTINUE TO
SEE SNOW WHILE LOWER ELEVATIONS SHOULD SEE A SHIFT TO RAIN. THE
ASSOCIATED COLD FRONT WILL CROSS TUESDAY AFTERNOON AND EVENING TO
BRING SNOW LEVELS BACK DOWN TO THE 1000 TO 2000 FOOT RANGE.
ALSO...SHADOWING SHOULD BEGIN TO TAKE EFFECT AFTER THE FRONT PASSES.

AHEAD OF...AND WITH THE COLD FRONT PASSAGE...SURFACE PRESSURE
GRADIENTS WILL INCREASE ACROSS THE SOUTHEASTERN TERRAIN. THIS WILL
CREATE BREEZY TO WINDY CONDITIONS ACROSS THE BLUE
MOUNTAINS...OCHOCO-JOHN DAY HIGHLANDS...THE GRANDE RONDE
VALLEY...AND WALLOWA COUNTY. THESE WINDS WILL ALSO CREATE AREAS OF
BLOWING AND DRIFTING SNOW WHICH WILL REDUCE VISIBILITIES DOWN TO
LESS THAN A MILE AT TIMES AND OCCASIONALLY TO LESS THAN 1/4 MILE.

BEGINNING TUESDAY EVENING...A SECOND SURGE OF MOISTURE WILL IMPACT
THE CASCADES WITH ENOUGH CONDITIONAL INSTABILITY TO ALLOW FREQUENT
SHOWERS TO CROSS OVER THE CASCADE EAST SLOPES THROUGH MOST OF
TUESDAY NIGHT. MOST OF THE MOISTURE WILL STAY NEAR THE CASCADES WITH
THE EXCEPTION OF THE FAR NORTHEAST MOUNTAINS. THE NORTHERN BLUE
MOUNTAINS AND WALLOWA COUNTY WILL CONTINUE TO SEE SIGNIFICANT SNOW
ACCUMULATIONS THROUGH THE MAJORITY OF WEDNESDAY MORNING.

NUMEROUS WARNINGS AND ADVISORIES HAVE BEEN ISSUED TO COVER THIS
EVENT. PLEASE REFER TO PDXNPWPDT FOR SPECIFIC DETAILS.  JBONK

LONG TERM...WEDNESDAY NIGHT THROUGH FRIDAY NIGHT.  THERE WILL BE A
BRIEF BREAK BETWEEN SYSTEMS WEDNESDAY NIGHT WITH THE NEXT SYSTEM
MOVING ACROSS THE AREA THURSDAY. A RIDGE BUILDS OVER THE EASTERN
PACIFIC WITH WEST TO NORTHWEST FLOW ON THURSDAY NIGHT AND FRIDAY
KEEPING A CHANCE OF PRECIPITATION MAINLY OVER THE BLUE MOUNTAINS IN
THE FAVORED UPSLOPE AREAS.  TEMPERATURES WILL BE NEAR NORMAL. 93

SATURDAY THROUGH MONDAY. A DISTURBANCE WILL RACE ACROSS THE REGION
SATURDAY AND SOME SHOWERS ARE POSSIBLE. A RIDGE OF HIGH PRESSURE
BUILDS INTO THE TWO STATE AREA SATURDAY NIGHT WITH DRIER CONDITIONS
EXPECTED INTO SUNDAY. THE RIDGE SHOULD REMAIN IN PLACE INTO THE
BEGINNING OF THE WORK WEEK AND BLOCK WEATHER SYSTEM FROM IMPACTING
THE AREA. HOWEVER...A DISTURBANCE MAY APPROACH THE WESTERN PORTIONS
OF THE AREA CLOSE ENOUGH TO PRODUCE SOME SHOWERS ALONG THE CASCADES
CREST OF OR/WA LATE MONDAY. TEMPERATURES SHOULD BE AT OR SLIGHTLY
ABOVE NORMAL FOR THE WEEKEND AND INTO NEXT WEEK.

AVIATION...MID AND LOWER LEVEL CLOUDS WILL INCREASE OVERNIGHT WITH
VFR CONDITIONS IN RAIN AND SNOW POSSIBLE AT KDLS...KRMD...KYKM BY
AROUND 8Z.  MVFR CONDITIONS WILL SPREAD EAST ACROSS REST OF AREA BY
12Z AND SOME PERIODS OF VFR DUE TO LOWER CEILINGS WITH RAIN AND SNOW
ARE EXPECTED TO LAST THROUGH THE DAY ON THURSDAY. 93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  31  38  29  41 /  40  90  30  20
ALW  32  40  31  41 /  40  90  30  20
PSC  31  40  29  39 /  40  80  30  10
YKM  26  36  26  35 /  90  80  40  10
HRI  31  38  28  40 /  40  80  30  10
ELN  24  32  23  33 / 100 100  40  10
RDM  26  39  22  37 /  90  90  50  30
LGD  26  33  29  34 /  30  90  40  30
GCD  25  35  25  35 /  90  90  40  20
DLS  32  38  31  40 / 100  90  70  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...HEAVY SNOW WARNING UNTIL 4 AM PST WEDNESDAY FOR ORZ042-043.

     SNOW AND BLOWING SNOW ADVISORY FROM 4 AM TUESDAY TO 10 AM PST
     WEDNESDAY FOR ORZ050.

     WINTER STORM WARNING FROM 4 AM TUESDAY TO 10 AM PST WEDNESDAY
     FOR ORZ502.

     WINTER STORM WARNING UNTIL 4 AM PST WEDNESDAY FOR ORZ503-506.

     SNOW AND BLOWING SNOW ADVISORY FROM 4 AM TUESDAY TO 4 AM PST
     WEDNESDAY FOR ORZ049.

     SNOW ADVISORY UNTIL 4 AM PST WEDNESDAY FOR ORZ504-505.

WA...HEAVY SNOW WARNING UNTIL 4 AM PST WEDNESDAY FOR WAZ026-501-502.

     WINTER STORM WARNING FROM 4 AM TUESDAY TO 10 AM PST WEDNESDAY
     FOR WAZ030.

     SNOW ADVISORY UNTIL 4 AM PST WEDNESDAY FOR WAZ027.

&&

TI:RYY
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
82/93/93

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
445 PM PST MON JAN 7 2008

UPDATED FOR WINTER HIGHLIGHTS

ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-081430-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
445 PM PST MON JAN 7 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...TONIGHT

HEAVY SNOW WARNING 10 PM TONIGHT THROUGH 4 AM WEDNESDAY
        EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST
        SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON,  KITTITAS
        VALLEY, NORTH CENTRAL OREGON, CENTRAL OREGON,

WINTER STORM WARNING 10 PM TONIGHT THROUGH 4 AM WEDNESDAY
        SOUTHERN BLUE MOUNTAINS OF OREGON,  OCHOCO-JOHN DAY
        HIGHLANDS

SNOW ADVISORY 10 PM TONIGHT THROUGH 4 AM WEDNESDAY
        YAKIMA VALLEY, NORTHERN WHEELER AND SOUTHERN GILLIAM
        COUNTIES, JOHN DAY BASIN

A VIGOROUS PACIFIC STORM IS MOVING ONSHORE AND WILL SPREAD
PRECIPITATION ACROSS THE EAST SLOPES OF THE CASCADES BEFORE MIDNIGHT
THEN OVER THE REMAINDER OF EASTERN WASHINGTON AND EASTERN OREGON
TUESDAY MORNING.  MODERATE TO HEAVY SNOW WILL FALL OVER THE
MOUNTAINS AND VALLEYS...AND VARIOUS WINTER HIGHLIGHTS HAVE BEEN
ISSUED.  PLEASE REFER TO THE LIST ABOVE AND THE
PRODUCT...PDXWSWPDT...FOR DETAILS.  THOSE UNDER A WINTER STORM
WARNING WILL EXPERIENCE HEAVY SNOW ALONG WITH BLOWING AND DRIFTING
SNOW CREATED BY BREEZY WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY

HEAVY SNOW WARNING THROUGH 4 AM WEDNESDAY
         EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON,
         EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON,
         KITTITAS VALLEY, NORTH CENTRAL OREGON, CENTRAL OREGON,

WINTER STORM WARNING 4 AM WEDNESDAY
         SOUTHERN BLUE MOUNTAINS OF OREGON, OCHOCO-JOHN DAY
         HIGHLANDS

WINTER STORM WARNING 4 AM TUESDAY THROUGH 10 AM WEDNESDAY
        NORTHERN BLUE MOUNTAINS OF OREGON, NORTHWEST BLUE
        MOUNTAINS OF WASHINGTON

SNOW ADVISORY THROUGH 4 AM WEDNESDAY
        YAKIMA VALLEY, NORTHERN WHEELER AND SOUTHERN GILLIAM
        COUNTIES, JOHN DAY BASIN

SNOW AND BLOWING SNOW ADVISORY 4 AM TUESDAY THROUGH 10 AM WEDNESDAY
        GRANDE RONDE VALLEY, WALLOWA COUNTY

THE STRONG AND MOIST PACIFIC STORM WILL BRING HEAVY SNOW OVER MOST
OF EASTERN WASHINGTON AND EASTERN OREGON TUESDAY AND TUESDAY NIGHT
WITH THE EXCEPTION OF THE COLUMBIA BASIN...THE BLUE MOUNTAIN
FOOTHILLS...AND THE EASTERN COLUMBIA RIVER GORGE.  PLEASE REFER TO
THE LIST ABOVE AND THE PRODUCT...PDXWSWPDT...FOR DETAILS.  THOSE
UNDER A WINTER STORM WARNINGS WILL EXPERIENCE HEAVY SNOW ALONG WITH
BLOWING AND DRIFTING SNOW CREATED BY BREEZY WINDS.

AN UNSETTLED WEATHER PATTERN WILL CONTINUE THROUGH MOST OF THE WEEK.
SHOWERS WILL LINGER WEDNESDAY IN THE MOUNTAINS. THEN CHANCES OF
PRECIPITATION WILL INCREASE AGAIN WEDNESDAY NIGHT AND THURSDAY WITH
THE ARRIVAL OF ANOTHER PACIFIC STORM. A WEAK WARM FRONT WILL MOVE
THROUGH THE REGION FRIDAY NIGHT AND SATURDAY. A RIDGE MAY BRING
DRIER CONDITIONS TO THE PACIFIC NORTHWEST SUNDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE LIKELY THROUGH WEDNESDAY.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.